Worksheetsemags
Total questions: 25
Worksheet time: 15mins
The potential field (voltage) at a certain point A due to a point charge that is located at another point B is ___ to the permittivity of the material in between.
Independent
Directly proportional
Inversely proportional
None of the above
If the voltage at point A with respect to a reference point X is VA and the voltage at point B with respect to a reference point X is VB, the potential difference VBA is equal to
VB − VA
VA + VB
VA − VB
both b and c
The capacitance per unit length of a coaxial __ if the dielectric material’s permittivity decreases.
Increases
Decreases
Remains the same
Cannot be determined. Not enough data.
The unit for material’s conductivity(σ).
S ∙ m
S⁄m
m⁄Ω
Ω ∙ m
Measures the amount of electric charge stored for a given electric potential.
Electric field intensity
Voltage
Capacitance
Current density
Which of the following equations defines the relation between electric field and voltage.
E = −(∇ ∙ V)
E = −(∇ × V)
E = −∇ ∙ (∇ × V)
E = −∇V
A capacitor can store 1 milli-joule at a potential difference of 5 V on its terminal leads when fully charge. Determine the capacitance.
40 μF
400 μF
80 μF
200 μF
The following statements is correct about electric dipole except for
Two point charges that are either both positive charge, or both negative charge.
Two point charges that are either both positive charge, or both negative charge.
The following statements is correct about electric dipole except for
None of the above
What will happen to the capacitance (C) of a capacitor if the external electric field decreases?
Decreases
Increases
Remains the same
Cannot be determined. Not enough information
An induced electric field within a dielectric material due to the external application of an electric field E is called ___. This electric field is generally weaker and opposite in direction to the applied E.
Dipole field
Dielectric field
Counter field
Polarization field
A parallel plate capacitor filled with mica having εr = 5. If the area of the parallel plate is six square meters and separation distance is 3.01 mm, determine the capacitance.
17.65 nF
14.71 nF
73.54 nF
88.25 nF
Ideally, dielectric materials have a conductivity of ___.
0
−∞
1
∞
Which of the following is the unit used for current density?
A ∙ m
A ∙ m^2
A⁄m
A⁄m^2
Determine the maximum energy stored for a 12 μF capacitor that accumulates 8 mC at maximum.
0.75 Joules
333.33 Joules
93.75 × 10−3
Joules
2.67 Joules
What will happen to the current density within a conductor if the electric field intensity affecting the material is increased?
Current density also increases
Current density will decrease
Current density won’t be affected
Cannot be determined. Not enough data.
An electric dipole has two point charges that has magnitude of 15 μC that is separated by a microscopic distance of 5 μm. Determine its dipole moment (p).
75 × 10^12 C ∙ m
150 × 10^12 C ∙ m
225 × 10^12 C ∙ m
3 × 10^12 C ∙ m
These are electric field bent outwards on the edge of capacitor’s plates.
Fringing fields
Non-uniform fields
Outside fields
Reactive fields
Calculate the total capacitance of a 20 meter long coaxial cable if the inner and outer conductor is air-separated and the radii are 2.2 mm and 6 mm, respectively.
55.45 pF
1.11 nF
11.89 nF
5.84 pF
A capacitor plates has dimensions of 5x6 cm and air-separated by a distance of 1mm. Calculate the capacitance of this capacitor.
26.56 × 10^−15 F
265.63 × 10^−6 F
26.56 × 10^−12 F
265.63 × 10^−9 F
If VA = 15 V at (2,2,2) and VB = 4 V at (3,5,3) when V = 0 V at origin, solve for VAB.
19 V
-19 V
-11 V
11 V
Given a cylindrical current density J = 1000ρz^2.5 az A⁄m^2 for region 0 ≤ ρ ≤ 3 mm ; for ρ > 3 mm, J = 0.
Determine the total current crossing the surface z = 0.5 m in the az direction.
12 mA
10 μA
8 μA
8 μA
A 20 nC point charge located at (2,2,2) in free space. Calculate VA if point A is located at origin and V = 0 is at infinity.
51.89 V
33.28 V
5.25 V
0 V
An electric field is expressed in rectangular coordinates by E = 3x^2 ax − 6y ay + 4z az V/m. Determine the voltage VAB if points A and B are A(−2,1,3) and B(0,2, −1), respectively.
−10 V
20V
−17 V
20V
Given a cylindrical current density J = 1000ρz^2.5 az A⁄m^2 for region 0 ≤ ρ ≤ 3 mm ; for ρ > 3 mm, J = 0.
If the charge velocity is 3 × 10^6 m⁄s at ρ = 3mm & z = 1.5 m, solve for volume charge density there.
3.56 μC
⁄m^3
10.75 μC
⁄m^3
5.67 μC
⁄m^3
2.76 μC
⁄m^3
A 20 nC point charge located at (2,2,2) in free space. Calculate VA if point A is located at origin and V = 0 is at (−1,3, −2).
16.64 V
35.25 V
51.89 V
18.61 V
